Goodwill and Intangible Assets (Schedule Of Intangible Assets) (Details) - USD ($) $ in Thousands	Jul. 31, 2019	Apr. 30, 2019	Jul. 31, 2018
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	$ 967,368	$ 872,195	$ 842,109
Accumulated Amortization	(547,977)	(529,702)	(487,278)
Net	419,391	342,493	354,831
Reacquired franchise rights
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	350,679	350,410	339,747
Accumulated Amortization	(141,954)	(136,345)	(119,386)
Net	208,725	214,065	220,361
Customer relationships
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	300,156	274,838	256,858
Accumulated Amortization	(203,283)	(195,174)	(171,542)
Net	96,873	79,664	85,316
Internally-developed software
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	144,768	139,239	137,914
Accumulated Amortization	(111,892)	(109,885)	(114,622)
Net	32,876	29,354	23,292
Noncompete agreements
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	40,358	33,376	32,888
Accumulated Amortization	(31,980)	(31,446)	(30,144)
Net	8,378	1,930	2,744
Franchise agreements
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	19,201	19,201	19,201
Accumulated Amortization	(13,654)	(13,334)	(12,374)
Net	5,547	5,867	6,827
Purchased technology
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	104,700	54,700	54,700
Accumulated Amortization	(45,166)	(43,518)	(39,210)
Net	59,534	11,182	15,490
Trade name
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	5,800
Accumulated Amortization	(48)
Net	5,752
Acquired assets pending final allocation
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	1,706	431	801
Accumulated Amortization	0	0	0
Net	$ 1,706	$ 431	$ 801